Negative attenuation amplifier discharge device



June 12, 1951 E. Mc 2,556,881

NEGATIVE ATTENUATION AMPLIFIER DISCHARGE DEVICE Filed My 24, 1950Invehtor: Elmer- D. McAr-thurz,

His Abbot-neg.

Patented June 12, 1951 NEGATIVE ATTENUATION AllIPLIFIER- DISCHARGEDEVICE Elmer D. McArthur, Schenectady, N. Y., assignor to GeneralElectric Company, a corporation of New York Application May 24, 1950,Serial No. 163,925

1 Claim.

My inventionrelates to electron discharge devices, and more particularlyto electron discharge devices employed as amplifiers of high frequencyelectromagnetic waves.

It is known that an ordinary transmission system, such, for example, asa wave guide or a coaxial cable, has inherent losses which cause anelectromagnetic wave to be attenuated upon passing therethrough. All ofthe sources of loss are commonly lumped into a factor called theattenuation constant which is a measure of how much the wave isdecreased in amplitude per unit distance of travel through the system.If this attenuation constant is made negative in sign, a wave passingthrough the system exhibits an increased amplitude.

It is, therefore, an object of my invention to provide a transmissionsystem which presents a negative attenuation to an electromagnetic wavepassing therethrough.

It is another object of myinvention to provide a wave guide structureexhibiting a negative impedance to electromagnetic waves havingfrequencies throughout a wide band width.

It is a further object of my invention to provide a new and improvedelectron discharge device having a negative impedance.

According to the illustrated embodiment of my invention, an electrondischarge device in the shape of a rectangular wave guide is providedwith an anode, a cathode, and a grid, each of which extendslongitudinally along the guide. The anode is maintained at a higherpositive potential than the cathode such that a direct electric fieldexists between the anode and the cathode. A high frequencyelectromagnetic wave is introduced atone end of the guide and travelsalong the guide parallel to the electrode structure. The dyotronprinciple is disclosed in application, Ser. No. 772,517, filed September6, 1947, entitled High Frequency Electric Systems Having High InputImpedance and Ser. No. 751,358, filed May 29, 1947, entitled ElectricDischarge Devices and High Frequency Systems Therefor, and which hasbeen abandoned, both being assigned to the assignee of the presentapplication. According to the dyotron principle, part of a highfrequency electric field established between the anode and the gridextends through the grid structure to the cathode, and may be used withan appropriate circuit arrangement to present a negative resistance tothe source of the high frequency field. In my amplifier, theelectromagnetic wave introduced into the guide establishes this electricfield and,

therefore, may be amplified by the device. My negative attenuation typeamplifier may be likened to a number of dyotron stages in cascade, andas the wave travels to each successive stage as it passes through theguide, it is further amplified. Consequently, the gain of the amplifieris related to the number of stages and hence to the length of thedevice.

For additional objects and advantages and for a better understanding ofmy invention, attention is now directed to the following description andaccompanying drawing and to the appended claim in which the featuresbelieved to be novel are particularly pointed out.

In the drawing, Fig. 1 shows a section of one embodiment of myinvention; Fig. 2 shows an end view of the device; Fig. 3 is asemi-transparent view of the device; and Fig. 4 is an end view showingthe electrode structure in detail.

Referring particularly to Fig. 4, an anode I extending the full lengthof and supported by one side of a hollow conductor or wave guidestructure 2 is insulated therefrom by insulation 3. Metallic plate 4 ismounted between guide 2 and insulation 3 and serves as one plate of acoupling capacitor comprising insulation 3 as the dielectric and anode Ias the other plate. An electric terminal 5 is connected to anode I andinsulated from guide 2 by an insulating bushing 6. A cathode I extendingthe full length of guide 2 is located opposite anode I and supported byan insulation member 8. A conventional filament type heater 9 extendsthe full length of cathode I and has input terminals III and I Iconnected at opposite ends thereof. A ceramic bushing I2 is located atthe approximate center of the guide and serves as a support for metallicterminal I3 which extends to the cathode 1 inside the guide. Amultiplicity of grid wires I4 are mounted parallel to each other betweencathode and anode I on metallic supports I5 and I6 which extend the fulllength of the guide. These supports also shield cathode I from anelectromagnetic wave in the guide except for a portion of the wave whichpasses through grid wires I4 to it. Insulators I1 and IS in combinationwith supports I5 and I6 and metallic strips I9 and 2!! capacitivelycouple grid M'to cathode 1.

Referring to Figs. 1, 2, and 3, the ends of the guide are hermeticallysealed by windows ZI and 22 which are made of a suitable material such,for example, as mica. An electromagnetic wave to be amplified isintroduced into the guide through window 2| and establishes an electricfield between grid 14 and anode i. The intensity of this field isrelated to the amplitude of the wave, and, therefore, the intensity ofthe field at any instant of time between any particular grid wire and aportion of the anode adjacent thereto is related to the amplitude of theelectromagnetic wave at such particular grid wire at that particularinstant of time. Because a negative resistance may be produced betweengrid l4 and anode I by adjusting the phase angle of the current flowbetween cathode I and anode l to the proper value as explained in thehereinbefore cited copending applications, a negative conductance willbe established across the inter-action space. By controlling the amountof current flow between cathode and anode and other controlling factorssuch, for example, as the number of grid wires per unit length, and thephase angle of the current with respect to the electric fieldestablished by the transmitted electromagnetic wave between grid and theanode, the negative resistance provided by dyotron action per unitlength of guide may be made greater than the inherent positiveconductance caused by the metal resistivity or other sources, and a wavepassing through this guide will be amplified.

This type amplifier has the advantage of simplicity of design, theability to be readily adapted to wave guide systems, and amplificationWhich is directly dependent upon its length, and no mechanicaladjustments which may be disturbed by such external effects asvibration. While my invention has been disclosed by means of aparticular device and construction, it will be understood that thoseskilled in the art may make many changes and modifications withoutdeparting from my invention, and, therefore, by the appended claim Iintend to cover any such modifications which fall within the true spiritand scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

An amplifier of high frequency electromagnetic waves comprising arectangularly shaped wave guide being provided therein with an anode anda cathode mounted on opposite faces of said guide, said anode and saidcathode extending the full length of said guide and being insulatedtherefrom, a pair of flat metallic shielding strips being mounted withinsaid guide and being located on opposite sides of said cathode, amultiplicity of parallel grid wires being mounted on said strips andbeing disposed transversely to the longitudinal axis of said wave guidebetween said anode and said cathode.

ELMER D. MCARTHUR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,122,538 Potter July 5, 19382,153,728 Southworth Apr. 11, 1939 2,411,535 Fremlin Nov. 26, 1946

